U.S. patent application number 14/673315 was filed with the patent office on 2015-10-01 for wheel drive system for aircraft.
This patent application is currently assigned to SINFONIA TECHNOLOGY CO., LTD.. The applicant listed for this patent is IHI AEROSPACE CO., LTD., SINFONIA TECHNOLOGY CO., LTD., SUMITOMO PRECISION PRODUCTS CO., LTD.. Invention is credited to Nobuyuki Nakanishi, Hitoshi Oyori, Hiroshi Saito, Masayuki Takada.
Application Number | 20150274285 14/673315 |
Document ID | / |
Family ID | 52807630 |
Filed Date | 2015-10-01 |
United States Patent
Application |
20150274285 |
Kind Code |
A1 |
Saito; Hiroshi ; et
al. |
October 1, 2015 |
WHEEL DRIVE SYSTEM FOR AIRCRAFT
Abstract
Provided is a wheel drive system for aircraft RS including a
motor 2 that is connected to a wheel 12, and provided with two
voltage supply lines L1 and L2 for supplying the voltages Vta and
Vpr with varying the length of a winding 21 to be energized; a
voltage supply unit for supplying the voltage Vta and Vpr to the
two voltage supply lines L1 and L2; and a control unit 8 for
controlling the voltage supply unit, wherein the control unit 8 is
configured to select one of the two voltage supply lines L1 and L2,
and supply the voltage Vta or Vpr, by controlling the voltage
supply unit.
Inventors: |
Saito; Hiroshi; (Tokyo,
JP) ; Nakanishi; Nobuyuki; (Tokyo, JP) ;
Oyori; Hitoshi; (Tokyo, JP) ; Takada; Masayuki;
(Amagasaki-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SINFONIA TECHNOLOGY CO., LTD.
IHI AEROSPACE CO., LTD.
SUMITOMO PRECISION PRODUCTS CO., LTD. |
Tokyo
Tokyo
Amagasaki-shi |
|
JP
JP
JP |
|
|
Assignee: |
SINFONIA TECHNOLOGY CO.,
LTD.
Tokyo
JP
IHI AEROSPACE CO., LTD.
Tokyo
JP
SUMITOMO PRECISION PRODUCTS CO., LTD.
Amagasaki-shi
JP
|
Family ID: |
52807630 |
Appl. No.: |
14/673315 |
Filed: |
March 30, 2015 |
Current U.S.
Class: |
244/50 |
Current CPC
Class: |
Y02T 50/823 20130101;
B64C 25/405 20130101; B64C 25/40 20130101; Y02T 50/80 20130101;
B64C 25/34 20130101 |
International
Class: |
B64C 25/40 20060101
B64C025/40; B64C 25/34 20060101 B64C025/34 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2014 |
JP |
2014-075751 |
Claims
1. A wheel drive system for aircraft, comprising a motor that is
connected to a wheel, and has two voltage supply lines for
supplying a voltage with varying a length of a winding to be
energized; a voltage supply unit that supplies a voltage to the two
voltage supply lines; and a control unit for controlling the
voltage supply unit, wherein the control unit is configured to
select one of the two voltage supply lines and supply a voltage to
the selected voltage supply line, by controlling the voltage supply
unit.
2. The wheel drive system for aircraft according to claim 1,
wherein a winding provided in the motor includes a dividing point
inside, and the two voltage supply lines comprise a first voltage
supply line that is connected to one end and the other end of the
winding, and a second voltage supply line that is connected to the
one end and the dividing point.
3. The wheel drive system for aircraft according to claim 2,
wherein the winding is configured by connecting a plurality of
winding elements in series, and the dividing point is set in any
one of connecting portions of adjacent winding elements.
4. The wheel drive system for aircraft according to claim 2,
wherein the voltage supply unit comprises a first voltage supply
unit for supplying a voltage to the first voltage supply line, and
a second voltage supply unit for supplying a voltage to the second
voltage supply line, and a circuit opening and closing unit for
opening and closing an electrical circuit configured between the
first voltage supply unit and the winding is provided on the first
voltage supply line.
5. The wheel drive system for aircraft according to claim 3,
wherein the voltage supply unit comprises a first voltage supply
unit for supplying a voltage to the first voltage supply line, and
a second voltage supply unit for supplying a voltage to the second
voltage supply line, and a circuit opening and closing unit for
opening and closing an electrical circuit configured between the
first voltage supply unit and the winding is provided on the first
voltage supply line.
6. The wheel drive system for aircraft according to claim 4,
wherein the motor has multiple phases, and has the winding for each
phase, one end of each winding is connected to each other at a
neutral point, and further connected to a power supply line through
the neutral point, and the wheel drive system further comprises a
neutral point connecting and disconnecting unit that enables an
electrical connection and disconnection between the neutral point
and one end of each winding.
7. The wheel drive system for aircraft according to claim 5,
wherein the motor has multiple phases, and has the winding for each
phase, one end of each winding is connected to each other at a
neutral point, and further connected to a power supply line through
the neutral point, and the wheel drive system further comprises a
neutral point connecting and disconnecting unit that enables an
electrical connection and disconnection between the neutral point
and one end of each winding.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority of Japanese Patent
Application No. 2014-075751 filed on Apr. 1, 2014. The contents of
the applications are incorporated herein by reference in their
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention relate to a wheel drive
system for aircraft for rotating a wheel of an aircraft.
[0004] 2. Description of the Related Art
[0005] Conventionally, an aircraft utilizes the power of an engine
for flight for movement in an airport (taxiing). Generally, a
moving speed obtained by such power is greater than a moving speed
for safe taxiing, and taxiing is done while braking by a brake.
Thus, consumption of fuel and wear of a brake by taxiing has been
questioned. For the purpose of suppressing these problems, a
proposal such as Patent Literature JP-T-2013-514229 below has been
made. The proposal includes a motor for rotating a wheel of an
aircraft, enables taxiing by rotating the wheel by the motor
without using an engine for an aircraft, and suppresses consumption
of energy and wear of a brake during taxiing.
[0006] Generally, a wheel of an aircraft stops rotation immediately
before touchdown, and rotates suddenly by the friction with a
runway immediately after touchdown. Then, the wheel is braked by a
brake, and it is possible to slow down a whole aircraft by
cooperating with other braking means such as an air brake. However,
a severe friction occurs between the wheel and the runway during
touchdown, and the wheel surface is greatly worn. For the purpose
of reducing such wear, a proposal such as Patent Literature
JP-A-2007-112408 has also been made. The proposal includes a motor
for rotating a wheel prior to landing (pre-rotation), relieves the
impact at touchdown, and suppresses the wear of a wheel by rotating
the wheel to meet a relative speed of a runway.
[0007] A taxiing speed of an aircraft described above is relatively
slow, approximately 35 km/h, and a large torque is required to move
a heavy aircraft. Thus, a motor is required to have a low-speed
high-torque output characteristic for rotating a wheel for
taxiing.
[0008] On the other hand, a touchdown speed of an aircraft upon
landing is relatively fast, 350 km/h or faster. It is sufficient to
rotate only a wheel in pre-rotation. Thus, a motor is required to
have a high-speed low-torque output characteristic for
pre-rotation.
[0009] Taxiing and pre-rotation are both technologies utilizing a
motor, but a required output characteristic is different. Thus, it
is difficult to use a common motor to achieve both taxiing and
pre-rotation.
[0010] In particular, when pre-rotation is performed by using a
motor for taxiing, a high-speed rotation of about 10 times faster
than taxiing is required, and a voltage of about 10 times greater
than taxiing is required. Thus, when a wheel drive system is
optimized according to a required voltage of a motor for taxiing, a
withstand voltage of an electronic device such as an inverter
provided in a voltage supply means exceeds an allowable value
during pre-rotation. Contrarily, when a wheel drive system is
optimized to meet a required voltage of a motor for pre-rotation,
characteristics of an electronic device provided in a voltage
supply means exceed those for taxiing, and production costs may
extremely increase.
SUMMARY OF THE INVENTION
[0011] The present invention has been made to effectively resolve
the above problems. In particular, it is an object of the invention
to provide a wheel drive system for aircraft, which properly
achieves both taxiing and pre-rotation by rotating a wheel by a
common motor, and suppresses production costs with a simple
configuration.
[0012] In order to achieve the above object, the present invention
has taken the following measures.
[0013] A wheel drive system for aircraft according to an embodiment
of the invention comprises a motor that is connected to a wheel,
and has two voltage supply lines for supplying a voltage with
varying a length of a winding to be energized; a voltage supply
unit that supplies a voltage to the two voltage supply lines; and a
control unit for controlling the voltage supply unit, wherein the
control unit is configured to select one of the two voltage supply
lines and supply a voltage to the selected voltage supply line, by
controlling the voltage supply unit.
[0014] In such a configuration, the control unit supplies a voltage
from the voltage supply unit, the motor is rotated, and the wheel
is rotated by the motor. By changing a destination of the voltage
supply of the voltage supply unit to one of the two voltage supply
lines, it is possible to change the length of a winding to be
energized. Thus, it is possible to obtain a low-speed high-torque
output characteristic when driving by increasing the winding
length, and obtain a high-speed low-torque output characteristic
when driving by decreasing the winding length. Therefore, it is
possible to perform taxiing of an aircraft at a low-speed
high-torque, and perform pre-rotation of a wheel before landing at
a high-speed low-torque by using a common motor. This suppresses an
increase in manufacturing costs with a simple configuration, and
achieves both taxiing and pre-rotation.
[0015] In order to reduce the size and weight of a motor by varying
the length of a winding to be energized by using the same winding,
it is preferable to provide a dividing point in the winding
provided in the motor, and to configure two voltage supply lines of
a first voltage supply line to be connected to one end and the
other end of the winding, and a second voltage supply line to be
connected to the one end and the dividing point.
[0016] In order to easily perform high-precision control by
precisely changing the motor output characteristics, it is
preferable to configure the winding by connecting a plurality of
winding elements in series, and to set the dividing point in any
one of the connecting portions of adjacent winding elements.
[0017] In order to construct a reliable system by suppressing an
occurrence of failure while simplifying a whole circuit, the
voltage supply unit preferably comprises a first voltage supply
unit for supplying a voltage to the first voltage supply line, and
a second voltage supply unit for supplying a voltage to the second
voltage supply line, wherein the first voltage supply line is
provided with a circuit opening and closing unit for opening and
closing an electrical circuit configured between the first voltage
supply unit and the winding.
[0018] In order to avoid an influence on a power supply line,
prevent an occurrence of a failure and malfunction in other
devices, and increase the safety, even if a fault occurs in a
voltage supply unit, a circuit opening and closing unit, and a
circuit or the like in a motor, it is preferable that the motor has
multiple phases, the winding is provided for each phase, one end of
each winding is connected to each other at a neutral point, and
further connected to a power supply line through the neutral point,
and a neutral point connecting and disconnecting unit, is further
provided to enable an electrical connection and disconnection
between the neutral point and one end of each winding.
[0019] According to the invention described above, it is possible
to provide a wheel drive system for aircraft, which properly
achieves both taxiing and pre-rotation by rotating a wheel using a
common motor, and suppresses production costs with a simple
configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a block diagram of a wheel drive system for
aircraft according to an embodiment of the invention.
[0021] FIG. 2 is a circuit diagram of the wheel drive system for
aircraft.
[0022] FIG. 3 is an explanatory diagram showing a part of the
circuit diagram shown in FIG. 2 used for taxiing.
[0023] FIG. 4 is an explanatory diagram showing a part of the
circuit diagram shown in FIG. 2 used for pre-rotation.
MODES FOR CARRYING OUT THE INVENTION
[0024] Hereinafter, embodiments of the present invention will be
described with reference to the drawings.
[0025] A wheel drive system for aircraft RS according to an
embodiment is configured as shown in FIG. 1. The wheel drive system
for aircraft RS is configured to rotate and drive a wheel 12 that
is supported by a support means 11 provided under an aircraft, and
is comprised of a motor 2 that is directly or indirectly connected
to the wheel 12, wherein the wheel 12 is rotated by the rotation of
the motor 2. Although the wheel 12 is shown only two in this
diagram, the wheel 12 may be provided in more number, and the power
of the motor 2 may be distributed to rotate the wheels. Further,
the diagram shows an example of wheel drive system for aircraft RS,
in which wheels 12 are assumed to be provided in one support means
11, and the wheels 12 are rotated. Generally, an aircraft is
provided with a plurality of such support means 11, and it is
preferable to configure the wheel drive system for aircraft RS for
each of the wheels 12 provided in each support means 11. In such a
case, if a control unit 8 described later is configured as a common
unit, it is possible to collectively control the wheels 12 provided
in different support means 11, and synchronously rotate them with
ease. This is more preferable.
[0026] As the motor 2, a permanent magnet synchronous motor is
used. A rotor (not shown) has a permanent magnet, and a stator (not
shown) have windings 21 for excitation (refer to FIG. 2). A rotor
is rotated by energizing the windings 21 by applying an AC voltage.
As long as required torque and rotational speed are obtained, the
motor is not limited to the permanent magnet synchronous motor. The
motor may be other appropriate types.
[0027] The motor 2 comprises two voltage supply lines L1 and L2 for
energizing the windings 21. It is possible to supply a voltage (a
taxiing voltage Vta) from a taxiing inverter 3, as a first voltage
supply means, through the first voltage supply line L1, and supply
a voltage (a pre-rotation voltage Vpr) from a pre-rotation inverter
4, as a second voltage supply means, through the second voltage
supply line L2. The taxiing inverter 3 and the pre-rotation
inverter 4 are configured to be supplied with power from a power
supply 7 that is configured as a DC power supply, and generate the
voltages Vta and Vpr required for rotating the motor 2 according to
a control instruction from the control unit 8.
[0028] A circuit opening and closing means 5 is provided in the
middle of an electrical circuit configured between the taxiing
inverter 3 and motor 2. The circuit opening and closing means 5 is
configured to open and close the electrical circuit based on an
instruction from the control unit 8.
[0029] The motor 2 has a neutral point Pn between the windings 21
(refer to FIG. 2) as described later. The neutral point Pn is
connected to a reference voltage line Vg that is one of the power
supply lines of the power supply 7. A breaker 6 as a neutral point
connecting and disconnecting means is provided between the neutral
point Pn and each winding 21. The breaker 6 is configured to open
and close the electrical circuit based on an instruction from the
control unit 8.
[0030] The control unit 8 comprises an ordinary microprocessor or
the like comprising a CPU, a memory, and an interface. The memory
previously stores programs required for processing. The CPU
sequentially retrieves and executes necessary programs, and
achieves the functions described above in cooperation with
peripheral hardware resources. A switching selection unit 81 is
included in the control unit 8. The switching selection unit 81
selects one of the inverters 3 and 4. The control unit 8 operates
one of the inverters 3 and 4, and supplies the motor 2 with the
taxiing voltage Vta or the pre-rotation voltage Vpr.
[0031] Hereinafter, the above configuration will be explained in
detail with reference to FIG. 2.
[0032] First, the motor 2 has three windings 21U, 21V, and 21E on
the stator side. By applying three AC voltages with different
phases to the windings 21U, 21V, and 21E, a rotating magnetic field
can be generated in the stator (not shown). The windings 21U, 21V,
and 21W have the same specifications. The winding 21 is configured
by serially connecting four winding elements (coils) 21a, 21b, 21c,
and 21d having the same winding length through the connecting
portions P1, P2, and P3. Here, the winding length represents the
length of the winding wound around an iron core or the like, and
has substantially the same meaning as the number of turns, as long
as the same core is used. One end Pa of each winding 21U, 21V, and
21W is connected at the neutral point Pn. One line 61 is comprised
of a conductor leading to the neutral point Pn from one end Pa of
each winding 21 (21U, 21V, 21W), and a conductor extending from the
neutral point Pn. Through the line 61, one end Pa of each winding
21 (21U, 21V, 21W) is connected to a reference voltage line Vg of
the power supply lines of the power supply 7.
[0033] Lines 33, 34, and 35 are drawn from the other end Pb of each
winding 21. The first voltage supply line L1 is comprised of the
lines 33, 34, 35, and the line 61 drawn from one end Pa of each
winding 21. Lines 43, 44, and 45 are drawn from the connecting
portion P1 nearest to the neutral point Pn out of the connecting
portions P1, P2, and P3 provided in each winding 21. The second
voltage supply line L2 is comprised of the lines 43, 44, 45, and
the line 61 drawn from one end Pa of each winding 21. In other
words, the connecting portion P1 divides only the winding element
21a, as a part of the entire winding 21, and functions as a
dividing point P1 that enables to energize only the winding element
21a.
[0034] The taxiing inverter 3 is supplied with power when connected
to a positive voltage line Vp and a negative voltage line Vn of the
power supply lines provided in the power supply 7. The taxiing
inverter 3 is configured to generate a three-phase taxiing voltage
Vta (refer to FIG. 1) by opening and closing six semiconductor
switching elements 31 provided inside. A smoothing capacitor 32 is
provided between the positive voltage line Vp and the negative
voltage line Vn, to stabilize the voltage. The taxiing inverter 3
is connected to the three lines 33 to 35, and connected to the
other ends Pb of the windings 21 (21U, 21V, 21W) through these
lines. Further, as described above, since one end Pa of each
winding 21 is connected to each other at the neutral point Pn
through the line 61, and connected to the reference voltage line Vg
through the neutral point Pn, the taxiing inverter 3 can apply an
AC voltage corresponding to the phases U, V and, W constituting the
taxiing voltage Vta, between one end Pa and the other end Pb of
each winding 21 (21U, 21V, 21W), and energize the entire winding 21
by the taxiing voltage Vta.
[0035] The circuit opening and closing means 5 is provided to
enable opening and closing of the electrical circuit configured
between the taxiing inverter 3 and the windings 21 (21U, 21V, 21W).
The circuit opening and closing means 5 is comprised of the
breakers 51 to 54 provided in the middle of the lines 33 to 35 and
61. These breakers 51 to 54 are configured to open and close an
electrical circuit according to an instruction from the control
unit 8 (refer to FIG. 1). When the electrical circuit is in a
closed state, the taxiing inverter 3 can supply a voltage to the
windings 21. When the electrical circuit is in an open state, the
electrical connection with the windings 21 is interrupted, and the
taxiing inverter 3 is protected, even if an excessive voltage
occurs at both ends of the winding 21. Further, the breakers 51 to
54 monitor the value of current flowing through the lines 33 to 35
and 61, and are automatically opened when the current value exceeds
a certain value. Thus, even when an overcurrent momentarily occurs,
the taxiing inverter 3 can be protected.
[0036] The pre-rotation inverter 4 has the same specifications as
the taxiing inverter 3. Similar to the taxiing inverter 3, the
pre-rotation inverter 4 is supplied with power when connected to a
positive voltage line Vp and a negative voltage line Vn of the
power supply lines provided in the power supply 7. The pre-rotation
inverter 4 is configured to generate a three-phase pre-rotation
voltage Vpr (refer to FIG. 1) by opening and closing six
semiconductor switching elements 41 provided inside. A smoothing
capacitor 42 is provided between the positive voltage line Vp and
the negative voltage line Vn. The pre-rotation inverter 4 is
connected to the three lines 43 to 45, and connected to the
connecting portion P1 provided in each winding 21 (21U, 21V, 21W)
through these lines. Further, as described above, since one end Pa
of each winding 21 is connected to each other at the neutral point
Pn through the line 61, and connected to the reference voltage line
Vg through the neutral point Pn, the pre-rotation inverter 4 can
apply an AC voltage corresponding to the phases U, V and, W
constituting the pre-rotation voltage Vpr, between one end Pa of
each winding 21 (21U, 21V, 21W) and the connecting portion Pb, that
is, at both ends of one winding element 21a, and energize only the
winding element 21a by the pre-rotation voltage Vpr.
[0037] On the lines drawn from one end of the Pa of each winding 21
(21U, 21V, 21W), on the way to the neutral point Pn, a breaker 6 as
a neutral point connecting and disconnecting means is provided
separately from the circuit opening and closing means 5. The
breaker 6 is also configured to connect and disconnect the line 61
according to an instruction from the control unit 8 (refer to FIG.
1). When the line 61 is disconnected, the electrical connection is
interrupted between one end Pa of each winding 21 (21U, 21V, 21W),
the neutral point Pn, and the reference voltage line Vg ahead
thereof. When the line 61 is connected, the electrical connection
is made between one end Pa of each winding 21 (21U, 21V, 21W), the
neutral point Pn, and the reference voltage line Vg ahead
thereof.
[0038] The following operation is possible by using the wheel drive
system for aircraft RS configured as above.
[0039] First, when moving an aircraft on a runway, that is, when
performing the taxiing, the part shown in FIG. 3 of the circuit
shown in FIG. 2 is operated. Hereinafter, an explanation will be
given by using FIG. 3 while referring to FIG. 1.
[0040] For performing the taxiing, the control unit 8 selects the
taxiing inverter 3 by the switching selection unit 81, and controls
the taxiing inverter 3. In particular, by opening and closing the
semiconductor switching element 31 provided in the taxiing inverter
3, the control unit 8 generates the three-phase taxiing voltage Vta
based on the DC voltage obtained from the power supply 7. At this
time, all semiconductor switching elements 41 provided in the
not-selected pre-rotation inverter 4 are opened, and no voltage is
supplied from the pre-rotation inverter 4.
[0041] Parallel to the control of the taxiing inverter 3, the
control unit 8 closes the breakers 51 to 54 constituting the
circuit opening and closing means 5, and closes the breaker 6.
[0042] Of the taxiing voltage Vta generated by the taxiing inverter
3, the AC voltages corresponding to the phases U, V, and W are
applied across both ends Pa and Pb of each winding 21 (21U, 21V,
21W). Each winding 21 comprises winding elements 21a to 21d
connected in series, and has about four times the length (the
number of turns) for each winding element 21a to 21d. Here, a
torque T obtained by the motor 2 when supplying a current I to a
winding having the number of turns K has the relation, T=KI. Thus,
comparing at the same current, when rotating the motor 2 by using
the taxiing inverter 3, it is possible to generate about four times
the torque when rotating the motor 2 by using the pre-rotation
inverter 4. Of course, the torque can be further increased by
increasing the energizing quantity. Since the winding 21 is formed
by connecting four same winding elements 21a to 21d, it is possible
to properly manage the ratio of the length of the entire winding 21
to the winding element 21a as an integer ratio, and minimize an
error in the rate of change in the output characteristics caused by
switching the destination of the voltage supply.
[0043] When rotating the motor 2 by using the taxiing inverter 3 as
described above, the motor 2 has a low-speed high-torque output
characteristic, and it is possible to properly perform the taxiing
by rotating the wheel 12 by the motor 2.
[0044] When an aircraft takes off after taxiing, the control unit 8
stops the voltage supply from the taxiing inverter 3, opens the
breakers 51 to 54, and the breaker 6 constituting the circuit
opening and closing means 5, and interrupts the electrical
connection between the taxiing inverter 3 and the windings 21. An
aircraft accelerates by using the driving force by a jet engine or
the like, and takes off. The rotational speed of the wheel 12
during takeoff reaches about 10 times during taxiing, and a high
counter electromotive voltage of about 10 times the voltage
supplied during taxiing occurs at both ends of each winding 21.
However, since the electrical connection is interrupted between the
taxiing inverter 3 and the windings 21 as described above, the
inverter 3 is protected without being influenced by the counter
electromotive voltage. A counter electromotive force occurs also at
both ends of the winding element 21a. However, as the length of the
winding element 21a is about 1/4 of the winding 21, the voltage is
small, and does not affect the pre-rotation inverter 4.
[0045] While an aircraft is normally flying, the control unit 8
stops the voltage supply from the taxiing inverter 3 and the
pre-rotation inverter 4. Thus, the motor 2 does not rotate, and the
wheel remains stopped.
[0046] When an aircraft is landing, prior to touchdown,
pre-rotation is performed to rotate the wheel 12. At that time, the
portion shown in FIG. 4 of the circuit shown in FIG. 2 is operated.
Hereinafter, an explanation will be given by using FIG. 4 while
referring to FIG. 1.
[0047] For performing the pre-rotation, the control unit 8 selects
the pre-rotation inverter 4 by the switching selection unit 81, and
controls the pre-rotation inverter 4. In particular, by opening and
closing the semiconductor switching element 41 provided in the
pre-rotation inverter 4, the control unit 8 generates the
three-phase pre-rotation voltage Vpr based on the DC voltage
obtained from the power supply 7. At this time, all semiconductor
switching elements 31 provided in the not-selected taxiing inverter
3 are opened, and no voltage is supplied from the taxiing inverter
3.
[0048] Parallel to the control of the pre-rotation inverter 4, the
control unit 8 closes the breakers 51 to 53 constituting the
circuit opening and closing means 5, and closes the breaker 54 and
breaker 6. In other words, as a part of the electrical circuit is
opened, the electrical connection is interrupted between the
taxiing inverter 3 and the windings 21, but the electrical
connection is made between one end Pa of each winding 21 (21U, 21V,
21W), the neutral point Pn, and the reference voltage line Vg ahead
thereof.
[0049] Of the pre-rotation voltage Vpr generated by the
pre-rotation inverter 4, the AC voltage corresponding to the phases
U, V, and W is applied to both ends of the winding element 21a
constituting the winding 21. The winding element 21a has about 1/4
of the length (the number of turns) of the entire winding 21. Thus,
When the same voltage is given, compared with the case of rotating
the motor 2 by using the taxiing inverter 3, the output torque
decreases, but the motor 2 can be rotated at a rotation speed of
about four times faster. Thus, it is possible to rotate the motor 2
at a rotational speed of about ten times merely by increasing the
output voltage Vpr from the pre-rotation inverter 4 to about 2.5
times the output voltage Vta from the taxiing inverter 3.
[0050] When rotating the motor 2 by using the pre-rotation inverter
4, the motor 2 has a high-speed low-torque output characteristic.
When performing the pre-rotation, the wheel 12 is not grounded, and
it is sufficient to rotate only the wheel 12. Thus, it is possible
to sufficiently serve the purpose by such an output characteristic.
It is possible to properly perform the pre-rotation by rotating the
wheel 12 by the motor 2.
[0051] As the wheel 12 is rotated at a high speed by the
pre-rotation, as during takeoff, a high counter electromotive
voltage occurs at both ends of each winding 21. However, since the
electrical connection is interrupted between the taxiing inverter 3
and the windings 21 as described above, the taxiing inverter 3 is
protected without being influenced by the counter electromotive
voltage.
[0052] At this time, when the breakers 51 to 53 fail for some
reason, and the electrical connection is interrupted between the
taxiing inverter 3 and the windings 21, the control unit 8 opens
the breaker 6, and functions as double prevention means so as not
to extend the influence of the failure of the breakers 51 to 53 to
the other parts. Further, even when a short circuit occurs in the
internal circuit of the motor 2, the control unit 8 remains the
breaker 6 open to interrupt the current.
[0053] The wheel 12 is rotated by friction with the runway at
touchdown, and a counter electromotive voltage occurs at both ends
of the winding element 21a. However, the counter electromotive
voltage remains at about the output voltage Vpr of the pre-rotation
inverter 4, and does not affect the semiconductor switching element
41 or the like constituting the pre-rotation inverter 4, and causes
no damages. On the other hand, a high counter electromotive voltage
occurs at both ends of each winding 21, but as in the case where
the wheel 12 is rotated by the pre-rotation, the electrical
connection is interrupted, and the taxiing inverter 3 is not
affected.
[0054] After an aircraft has landed and fully decelerated, the
taxiing is performed up to a predetermined position, but it is
sufficient to perform the same control as before the take-off.
[0055] As described above, the wheel drive system for aircraft RS
according to the embodiment is characterized by comprising the
motor 2 that is connected to the wheel 12, and provided with two
voltage supply lines L1 and L2 for supplying the voltages Vta and
Vpr with varying the length of the winding 21 to be energized; the
taxiing inverter 3 and the pre-rotation inverter 4 as voltage
supply means for supplying the voltage Vta and Vpr to the two
voltage supply lines L1 and L2; and the control unit 8 for
controlling the taxiing inverter 3 and the pre-rotation inverter 4,
wherein the control unit 8 is configured to select one of the
voltage supply lines L1 and L2, and supply the voltage Vta or Vpr
to the selected voltage supply line L1 or L2, by controlling the
taxiing inverter 3 and the pre-rotation inverter 4.
[0056] Being configured as above, the control unit 8 supplies the
voltage Vta and Vpr from the taxiing inverter 3 and the
pre-rotation inverter 4, the motor 2 is rotated thereby, and the
wheel 12 can be rotated by the motor 2. It is also possible to
change the energizing length of the winding 21 by changing the
destination of the supply voltages Vta and Vpr from the taxiing
inverter 3 and the pre-rotation inverter 4 to one of the two
voltage supply lines L1 and L2. Thus, the low-speed high-torque
output characteristic is obtained when driving by increasing the
winding length, and the high-speed low-torque output characteristic
is obtained when driving by decreasing the winding length. It is
possible to perform taxiing an aircraft at a low-speed high-torque
and pre-rotation of the wheel 12 at a high-speed low-torque before
landing by using the common motor 2. Therefore, it is possible to
achieve both taxiing and pre-rotation while suppressing an increase
in manufacturing costs with a simple configuration.
[0057] The dividing point P1 is set in the winding 21 provided in
the motor 2. The voltage supply lines L1 and L2 are comprised of
the first voltage supply line L1 connected to one end Pa and the
other end Pb of the winding 21, and the second voltage supply line
L2 connected to one end Pa and the dividing point P1. Thus, it is
possible to apply the voltages Vta and Vpr obtained from the
taxiing inverter 3 and pre-rotation inverter 4 across the both ends
Pa and Pb of the winding 21 through the first voltage supply line
L1, and across one end Pa and the dividing point P1 of the winding
21 through the second voltage supply line L2. Therefore, it is
possible to change the length of the winding 21 to be energized by
using the same winding 21, and the size and weight of the motor 2
can be reduced.
[0058] Further, the winding 21 is configured by connecting a
plurality of winding elements 21a to 21d in series, and the
dividing point P1 is set in any one of the connecting portions P1,
P2, and P3 between the adjacent winding elements 21a and 21b, 21b
and 21c, and 21c and 21d. Thus, it is possible to manufacture by
exactly managing the ratio of the winding elements 21a to 21d to
the entire winding 21, and to change the output characteristic with
high accuracy by switching the winding 21 to be energized.
Therefore, it is possible to easily perform a high-precision
control.
[0059] As a voltage supply means, there are provided the taxiing
inverter 3 as a first voltage supply means for supplying the
voltage Vta to the first voltage supply line L1, and the
pre-rotation inverter 4 as a second voltage supply means for
supplying the voltage Vpr to the second voltage supply line L2. The
circuit opening and closing means 5 for opening and closing the
electrical circuit configured between the taxiing inverter 3 and
the winding 21 is provided on the first voltage supply line L1.
This eliminates the necessity of a complex circuit configuration,
such as, switching the connection destination by using a common
voltage supply means. Thus, it is possible to construct a highly
reliable system by simplifying the whole circuit. When rotating the
motor 2 at a high speed by supplying the voltage Vpr from the
pre-rotation inverter 4, the circuit opening and closing means 5
opens the electrical circuit configured between the taxiing
inverter 3 and the winding 21, to prevent application of an
excessive counter electromotive voltage to the taxiing inverter 3,
thereby avoiding damage to the equipment.
[0060] The taxiing inverter 3 and the pre-rotation inverter 4 have
the same specifications. This facilitates management of production
and maintenance. Further, combining with the configuration able to
change the length of the winding 21 to be energized by the taxiing
inverter 3 and the pre-rotation inverter 4, it is possible to
change the characteristics of the motor 2 without greatly changing
the voltages Vta and Vpr supplied from the inverters 3 and 4. This
eliminates the necessity of using expensive equipment corresponding
to the control in a wide voltage range, and suppresses an increase
in manufacturing costs.
[0061] In addition, the motor 2 has multiple phases U, V, and W,
and has the windings 21 for each of the phases U, V, and W. One end
Pa of each winding 21 is connected to each other at the neutral
point Pn, through which the motor 2 is connected to the reference
voltage line Vg constituting the power supply line. The motor 2
further comprises the breaker 6 as a neutral point connecting and
disconnecting means that enables an electrical connection and
disconnection between the neutral point Pn and one end Pa of each
winding 21. Thus, even when a failure occurs in the taxiing
inverter 3, the pre-rotation inverter 4, the circuit opening and
closing means 5, or the internal circuit or the like of the motor
2, the breaker 6 cuts off the connection between one end Pa of each
winding 21, the neutral point Pn, and the reference voltage line VG
ahead thereof. Therefore, it is possible to avoid an influence to
the power supply 7, prevent a failure and malfunctions in the other
devices, and enhance the safety of aircraft.
[0062] The specific structure of each part is not intended to be
limited only to the embodiment described above.
[0063] For example, in the embodiment described above, the winding
21 comprises four winding elements 21a to 21d of the same length.
As long as the winding comprises a plurality of winding elements,
the same effects can be obtained. In other words, the winding 21 is
comprised of n number of winding elements, a line is drawn out from
the dividing point P1 that can divide the winding into one winding
element and the n-1 number of winding elements, and a part for
applying a voltage is switched. In this way, the output torque can
be changed at the ratio of 1:n. When the value of n is increased to
4 or greater, it is possible to increase the difference between the
low-speed high-torque output characteristic and the high-speed
low-torque output characteristic.
[0064] Further, the dividing point for dividing the winding 21 is
not necessary to be the closest to the neutral point Pn, and may be
appropriately changed.
[0065] When the request to the small size and light weight of the
motor 2 is small, a long winding and a short winding may be
incorporated in each separate stator. The first voltage supply line
L1 may be connected to the long winding, and the second voltage
supply line L2 may be connected to the short winding. It is
possible to obtain the same effects as those described above also
in this case.
[0066] Further, in the embodiment described above, the motor 2 is
configured as a three-phase motor that is rotated by a three-phase
AC voltage. In principle, the same configuration is possible with
either a single-phase motor or a multiphase motor other than a
three-phase motor. The same effects can be obtained in this
case.
[0067] In the embodiment described above, the taxiing inverter 3
and pre-rotation inverter 4 are connected to the first voltage
supply line L1 and second voltage supply line L2, respectively. It
is possible to configure the taxiing inverter 3 and pre-rotation
inverter 4 by a common inverter, and use the inverter in switching
to the first voltage supply line L1 for the taxiing, and the second
voltage supply line L2 for the pre-rotation. The same effects can
also be obtained in this case.
[0068] For the other configurations, the present invention can be
variously modified without departing from the scope of the
invention.
* * * * *